West Coast. Saldanha Bay To Generate Own ElectricityNovember 24, 2010 by: admin
This became clear at well attended information session, organised by the West Coast Chapter of the Cape Chamber of Commerce.
Development on the West Coast has always been restricted by the lack of natural water supplies, but Alexander Horvath of the Dutch firm Norit said water could be desalinated in a reverse osmosis plant at a cost of just R4 per kl (one cubic metre) and R1.90 cents in a more complex plant which also recycled used water.
This is well below the present retail price of water. Retail water prices increase in a “stepped tariff” scale with the price per kilolitres increasing as more water is used. At present retail prices for water in Cape Town range from R4.55c to R23.42c per kilolitre.
Horvath said that at present nine percent of the water consumed in the world was desalinated. He explained that desalination would bring other benefits as the waste brine would be processed to extract rare minerals such as Lithium and Magnesium before the remainder was discharged into the open ocean.
In fact the water returned to the sea would be cleaner than the water taken from it as it would be stripped of heavy metals. Although there would be a concentration of salt at the discharge points, this would be rapidly dissipated in the open sea.
He made it clear that there would be no uptake from the bay or the lagoon and there would be no discharge into the sheltered water.
Norit plan to dilute the sea water with treated recycled water and this will reduce the cost of the desalination process which is more efficient when salt concentrations are lower. The resulting fresh water from the reverse osmosis plant will be superior to present municipal water.
It also became clear that the IDZ would not be relying on Eskom to provide electricity. Instead the plan is to use gas to generate baseload power and to supplement this with electricity from wind turbines, concentrated solar plants and photo voltaic panels.
The alternate power sources are becoming more cost effective as the technology improves and the economies of scale bring down costs.
Several sources of gas are being considered. These include imported natural gas, gas from our own off-shore fields, coal bed methane and, in future, shale gas. At present, however, the old fashioned “town gas” made from coal is preferred. The gas would be produced near the coal fields in the north and railed to Saldanha.
An interesting possibility is that the desalination plant could be run entirely on wind or solar power. This is becomes possible as water can be desalinated when wind or solar power is available and the water can be stored in reservoirs for use as required.
One of the problems with wind turbines is that that they often generate power at night when the demand for electricity is low. This “night power” could, however, be used for desalination.
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